1. Field of the Invention
The present invention generally relates to a zoom lens system, and more particularly to an improvement of the focusing system thereof.
2. Description of the Prior Art
In this field of art, there has been known a popular type of zoom lens system which comprises a front focusing lens group, a variator lens group, a compensator lens group and a rear master lens group. However, the front lens group has been of a refractive power within a relatively restricted range with its function of focusing taken into consideration, and a free selection of the refractive power of the front lens group for the sole purpose of aberration correction has not been permitted. Further, the radius of the front lens group has been relatively great for covering the light rays upon its shift to the object side in close focusing, which contradicts the demand for the compactness of the system.
The prior art is still seeking to provide an improvement of the focusing system of zoom lens systems.